Australian Facetors' Guild Limited

On the GF3 the angle splitter will give you tenths of a degree and you can do a little bit of interpolation. - anyone who believes that they are actually setting their digital device to hundredths of a degree is living in fantasy land.

Hi Stephen

Hi Stephen

You can use a triangle to set the angle

Measure the distance from a known point on the Quill to the point where the line running down the centre of the Quill would intersect a line in the centre of the mast. 

Then to work out the angle once you’ve set the angle you measure the distance of a right angle from the centre of the mast to the point on the Quill that you first measured to. 

The first measurement is of the hypotenuse of a triangle and the second measurement is of the base of a triangle. Then use the correct formula to calculate the angle at the tip. I’m not sure if it is sign or cos, but you can look it up. 

to set the angle you do the reverse you use the formula to calculate the length of the base for the angle that you want as the hypotenuse is always constant what you have that legs use a verniers calipers to position the depth gauge at the distance where the quill has to stop for the angle that you want.

Bruce, by the way because Facetron and VJ set the angle using gears, you can repeatable set the angle to a set hundredth of a degree.  The new Halls aren’t as accurate because although the dial indicator is calibrated to a hundredth of a degree, it relies on the angle first being set each time the angle.  The manufacturer says he has measured the setting error and a Facetors using a 10x loupe to set the angle can got to within -+ 0.03 degrees.

Anyway it is reapply only relevant to get close when Polishing.  0.01degree accuracy is finer than the surface error on most laps so the angle changes as you sweep the lap.